Method for the low-loss production of multi-component wafers

ABSTRACT

The present invention relates to a method for producing a multi-component wafer, in particular a MEMS wafer. The method according to the invention comprises at least the following steps: providing a bonding wafer ( 2 ), wherein at least one surface portion ( 4 ) of the bonding wafer ( 2 ) is formed by an oxide film, providing a dispenser wafer ( 6 ), wherein the dispenser wafer ( 6 ) is thicker than the bonding wafer ( 2 ), bringing the dispenser wafer ( 6 ) into contact with the surface portion ( 4 ) of the bonding wafer ( 2 ) that is formed by the oxide film, forming a multilayer arrangement ( 8 ) by connecting the dispenser wafer ( 6 ) and the bonding wafer ( 2 ) in the region of the contact, producing modifications ( 18 ) in the interior of the dispenser wafer ( 6 ) for predefining a detachment region ( 11 ) for separating the multilayer arrangement ( 8 ) into a detaching part ( 14 ) and a connecting part ( 16 ), wherein the production of the modifications ( 18 ) takes place before the formation of the multilayer arrangement ( 8 ) or after the formation of the multilayer arrangement ( 8 ), separating the multilayer arrangement along the detachment region as a result of a weakening of the multilayer arrangement brought about by the production of a sufficient number of modifications or as a result of production of mechanical stresses in the multilayer arrangement, wherein the connecting part ( 16 ) remains on the bonding wafer ( 2 ) and wherein the split-off detachment part ( 14 ) has a greater thickness than the connecting part ( 16 ).

The present invention relates according to claim 1 to a method forproducing a multi-component wafer, in particular a MEMS wafer, accordingto claim 14 to a use of a substrate as donor wafer and bonding wafer ina multi-component production method, in particular a MEMS waferproduction method, and according to claim 15 to a multi-component wafer,in particular a MEMS wafer.

In many technical fields (for example microelectronics or photovoltaictechnology) materials such as silicon, germanium or sapphire are oftenused in the form of thin slices and plates (what are known as wafers).As standard, wafers of this kind are currently produced by sawing froman ingot, wherein relatively large material losses (“kerf loss”) areincurred. Since the used starting material is often very costly, it ishighly sought to produce wafers of this kind with less materialconsumption and therefore more efficiently and more economically.

By way of example, with the currently conventional methods, almost 50%of the used material is lost as “kerf loss” in the production of siliconwafers for solar cells alone. Considered globally, this corresponds toan annual loss of more than 2 billion euros. Since the costs of thewafer account for the largest share of the cost of the finished solarcell (over 40%), the costs of solar cells could be significantly reducedby corresponding improvements in the wafer production.

Methods which dispense with the conventional sawing and for example candirectly split off thin wafers from a thicker workpiece by use oftemperature-induced stresses appear to be particularly attractive forwafer production of this kind without kerf loss (“kerf-free wafering”).These include in particular methods as described for example inPCT/US2008/012140 and PCT/EP2009/067539, where a polymer layer appliedto the workpiece is used in order to produce these stresses.

Particularly high material losses occur with the production ofmulti-component wafers, for example what are known as MEMS wafers(microelectromechanical systems wafer). The production of wafers of thiskind presupposes the use of a number of very thick starting wafers, theproduction of which generally already causes significant materiallosses. The great thickness of the starting wafer is required becauseonly in this way can bow and warp be kept low enough. In the case ofMEMS wafers, a starting wafer is usually used to cover an oxide layer ona further starting wafer, at the same time establishing an integrallybonded connection. Once the integrally bonded connection has beenestablished, there is always a machining treatment of the starting waferin order to significantly reduce the thickness thereof to the smallersize necessary for use, thus resulting in turn in material losses.

The object of the present invention is therefore to reduce the materialconsumption in multi-component wafer production, in particular MEMSwafer production.

The aforementioned object is achieved in accordance with the inventionby a method according to claim 1. The method according to the inventionfor producing a multi-component wafer, in particular a MEMS wafer,preferably comprises at least the following steps:

The method according to the invention preferably comprises at least thefollowing steps: providing a bonding wafer, wherein at least one surfaceportion of the bonding wafer is formed by an oxide layer, providing adonor wafer, wherein the donor wafer is thicker than the bonding wafer,bringing the donor wafer into contact with the surface portion of thebonding wafer that is formed by the oxide layer, forming a multilayerarrangement by connecting the donor wafer and the bonding wafer in theregion of the contact, producing modifications in the interior of thedonor wafer for predefining a detachment region for separating themultilayer arrangement into a separation part and a connection part,wherein the production of the modifications takes place before theformation of the multilayer arrangement or after the formation of themultilayer arrangement, separating the multilayer arrangement along thedetachment region as a result of a weakening of the multilayerarrangement brought about by the production of a sufficient number ofmodifications or as a result of production of mechanical stresses in themultilayer arrangement, wherein the connecting part remains on thebonding wafer, and wherein the split-off separation part has a greaterthickness than the connection part. Additionally or alternatively,individual steps or groups of steps of the aforementioned method can bereplaced or supplemented by the following steps: providing a bondingwafer, wherein at least one surface portion of the bonding wafer isformed by an oxide layer, providing a donor wafer, wherein the donorwafer is thicker than the bonding wafer, bringing the donor wafer intocontact with the surface of the bonding wafer that is formed by theoxide layer, forming a multilayer arrangement by connecting the donorwafer and the bonding wafer in the region of the contact, arranging orproducing a stress-producing layer on at least one exposed planarsurface of the multilayer arrangement, thermally treating thestress-producing layer in order to produce mechanical stresses withinthe multilayer arrangement, wherein the stresses in the portion of themultilayer arrangement formed by the donor wafer are large enough that acrack forms in the donor wafer, by means of which the donor wafer issplit into a separation part and a connection part, wherein theconnection part remains on the bonding wafer, and wherein the split-offseparation part has a greater thickness than the connection part.

This solution is advantageous since the donor wafer is not reduced bymachining of the connection portion, and instead is divided by a crackinto two parts, thus resulting in a separation part, which can be usedfurther. This makes it possible for the starting wafers, or the bondingwafer and the donor wafer, to be connected to one another, and morespecifically each can have a great thickness, but without having toexperience the material losses known from the prior art.

Further preferred embodiments are the subject of the following parts ofthe description and/or the dependent claims.

In accordance with a preferred embodiment of the present invention, themethod according to the invention comprises the step of cleaning theseparation part and/or the step of converting the separation part into afurther bonding wafer by treatment of at least one surface portion, andpreferably the entire surface, of the separation part. The bonding waferthus produced is then particularly preferably provided as a furtherbonding wafer to be brought into contact with a further donor wafer.This embodiment is advantageous since the starting wafer is used insuccession as a donor wafer, i.e. firstly as a donor wafer, and as abonding wafer, i.e. after the use as donor wafer.

The treatment, in accordance with a further preferred embodiment of thepresent invention, comprises an SiOx process, whereby an oxidation ofthe at least one surface portion of the bonding wafer is effected. Thisembodiment is advantageous since the oxide layer necessary for amulti-component wafer, in particular a MEMS wafer, is produced easily ina defined manner. Here, it is conceivable that a multiplicity of wafersor separation parts are treated in a treatment space in succession or atthe same time for production of the oxide layer(s).

In accordance with a further preferred embodiment of the presentinvention, the donor wafer has a first thickness D1, the bonding waferhas a second thickness D2, the separation part has a third thickness D3,and the connection part has a fourth thickness D4, wherein the thicknessD1 is greater than the sum of the thicknesses D3 and D4, and wherein thesum of the thicknesses D3 and D4 is greater than the thickness D3, andwherein the thickness D3 is greater than the thickness D2 by a thicknessDL. The thickness D2 is here preferably greater than 300 μm andpreferably greater than 400 μm or 500 μm or 600 μm or 700 μm. thisembodiment is advantageous since very stable elements, such as thebonding wafer, the donor wafer and/or the separation part, can be used,whereby these elements for example withstand the mechanical stressesoccurring during an optional polishing step. Elements or wafers of suchthickness also form much smaller warps and bows than thinner wafers.

The thickness DL, in accordance with a further preferred embodiment ofthe present invention, is less than 200 μm, in particular less than 100μm, for example less than 90 μm or less than 80 μm or less than 70 μm orless than 60 μm or less than 50 μm, and is preferably removed as aresult of polishing and/or etching steps or is as large as the materialportions removed by means of polishing and/or etching treatment. Thisembodiment is advantageous since a thickness necessary for the surfacetreatment is provided, which thickness is sufficient to create a planarsurface and at the same time only causes extremely small materiallosses.

In accordance with a further preferred embodiment of the presentinvention, the method according to the invention comprises the step ofproducing modifications for predefining the course of the crack. Themodifications are preferably produced before the multilayer arrangementis formed or after the multilayer arrangement is formed. Themodifications are preferably produced by means of laser beams or ionradiation in the interior of the donor wafer. The laser beams arepreferably emitted from a LASER device, wherein the LASER device ispreferably a picosecond laser or a femtosecond laser. Additionally oralternatively, it is conceivable that the modifications are local cracksin the crystal lattice and/or material portions in the interior of thedonor wafer that have been converted into another phase as a result of atreatment.

The LASER device, in accordance with a further preferred embodiment ofthe present invention, comprises a femtosecond LASER (fs LASER), and theenergy of the LASER beams of the fs LASER is preferably selected in sucha way that the propagation of damage of each modification in the toplayer and/or the sacrificial layer is less than 3 times the Rayleighlength, preferably less than the Rayleigh length, and particularlypreferably less than a third of the Rayleigh length and/or thewavelength of the LASER beams of the fs LASER is selected in such a waythat the absorption of the top layer and/or of the sacrificial layer isless than 10 cm⁻¹ and preferably less than 1 cm⁻¹ and particularlypreferably less than 0.1 cm⁻¹ and/or the individual modifications areproduced in each case as a result of a multi-photon excitation broughtabout by the fs LASER.

In accordance with a further preferred embodiment of the presentinvention, the laser beams for producing the modifications penetrate asurface of the donor wafer which is part of the connection part orbelongs to the portion which is thinner than the other portion once thedonor wafer has been divided into two portions as a result of theformation of a crack. This embodiment is advantageous since the laserbeams have to move less far through a solid body than if they had tomove through the other portion. In particular, an energy saving on thepart of the laser is hereby possible, and an undesirable heating of thedonor substrate as a result of the production of the modification ispreferably reduced.

The method according to the invention preferably comprises the steps ofarranging or producing a stress-producing layer on at least one exposedsurface of the multilayer arrangement and the step of thermally treatingthe stress-producing layer in order to produce the mechanical stresseswithin the multilayer arrangement, wherein the stresses in the portionof the multilayer arrangement formed by the donor wafer are so greatthat a crack forms in the donor wafer along the detachment region, bymeans of which crack the donor wafer is split into the separation partand the connection part, wherein the stress-producing layer comprises orconsists of a polymer, in particular polydimethylsiloxane (PDMS),wherein the thermal treatment is performed in such a way that thepolymer experiences a glass transition, wherein the stress-producinglayer is temperature-controlled, in particular by means of liquidnitrogen, to a temperature below room temperature or below 0° C. orbelow −50° C. or below −100° C. or below −110° C., in particular to atemperature below the glass transition temperature of thestress-producing layer.

This embodiment is advantageous since it has been found that, due to thethermal treatment of the stress-producing layer, in particular byutilisation of the property changes of the material of thestress-producing layer occurring with the glass transition, the forcesnecessary to initiate and form a crack can be produced in a donorsubstrate. Furthermore, by means of the thermal treatment of thestress-producing layer, it is possible to very precisely control, intime, the moment at which the solid-body layer will be separated or thetime at which the multilayer arrangement will be divided.

The mechanical stresses can be produced additionally or alternatively byon the whole mechanical vibrations and/or temperature variations and/orpressure changes, in particular atmospheric pressure changes.

The substrate or the donor wafer preferably comprises a material or amaterial combination from one of the main groups 3, 4 and 5 of thePeriodic Table of Elements, such as Si, SiC, SiGe, Ge, GaAs, InP, GaN,Al2O3 (sapphire), AlN, or consists of one or more of these materials.The substrate or the donor wafer particularly preferably comprises acombination of elements occurring in the third and fifth group of thePeriodic Table of Elements. Conceivable materials or materialcombinations are for example gallium arsenide, silicon, silicon carbide,etc. Furthermore, the substrate or the donor wafer can comprise aceramic (for example Al2O3—aluminium oxide) or can consist of a ceramic,preferred ceramics being for example perovskite ceramics (such as Pb—O—,Ti/Zr-containing ceramics) in general, and lead magnesium niobates,barium titanate, lithium titanate, yttrium aluminium garnet, inparticular yttrium aluminium garnet crystals for solid-body LASERapplications, SAW (surface acoustic wave) ceramics, such as lithiumniobate, gallium orthophosphate, quartz, calcium titanate, etc., inparticular. The substrate or the donor wafer thus preferably comprises asemiconductor material or a ceramic material, or the substrate or thedonor wafer particularly preferably consists of at least onesemiconductor material or a ceramic material. It is also conceivablethat the substrate or the donor wafer comprises a transparent materialor partially consists of or is made of a transparent material, such assapphire. Further materials which can be considered here as solid-bodymaterial alone or in combination with another material are for example“wide band gap” materials, InAlSb, high-temperature superconductors, inparticular rare earth cuprates (for example YBa2Cu3O7).

The present invention, according to claim 9, also relates to a use of asubstrate as donor wafer and bonding wafer in a multi-component waferproduction method, in particular a MEMS wafer production method. Thesubstrate is preferably arranged as donor wafer on a further bondingwafer, which has an oxidation layer, wherein the donor wafer is dividedby being split into a connection part and a separation part as a resultof the propagation of a crack, and wherein the separation part serves asbonding wafer after treatment in an oxidation process, in particular anSiOx process, wherein the bonding wafer is connected to a further donorsubstrate in order to form a multilayer arrangement.

The present invention also relates to a multi-component wafer, inparticular a MEMS wafer, according to claim 10. The multi-componentwafer according to the invention comprises at least one bonding wafer,wherein at least one surface portion of the bonding wafer is formed byan oxide layer, a connection part split off from a donor wafer as resultof the propagation of a crack, wherein the connection part is arrangedin an integrally bonded manner on a surface portion formed by the oxidelayer, and wherein the bonding wafer is a portion, processed by means ofan oxidation treatment, in particular an SiOx treatment, of a separationpart separated from a donor wafer.

The multi-component wafer according to the invention can be referred toalternatively for example as a MEMS wafer or as a silicon-on-insulatorwafer or as a multilayer wafer or as wafer with inner bonding layer. Itis merely essential here that an oxide layer is created or produced orformed or brought about or arranged as insulator layer or bonding layeror etching stop layer between two further layers or material portions.The further layers or material portions particularly preferably form onthe one hand the bonding wafer and on the other hand the donor wafer.The bonding wafer and the donor wafer, in the portions neighbouring theinsulator layer or bonding layer or etching stop layer, preferablyconsist of the same material and/or of a semiconductor material.However, it is also conceivable that the bonding wafer and the donorwafer, in the portions neighbouring the insulator layer or bonding layeror etching stop layer, consists of different materials, in particular ofone or more semiconductor materials, or comprises these materials. Theoxide layer, which particularly preferably serves as insulator layer orbonding layer or etching stop layer, preferably has a thickness, inparticular an average thickness or a minimum thickness or a maximumthickness, of at least or precisely or at most 1.25 μm or 1.5 μm or 1.75μm or 2 μm or 2.25 μm or 2.5 μm or 2.75 μm or 3 μm or 4 μm or 5 μm or 6μm or 7 μm or 7.5 μm or 8 μm or 9 μm or 10 μm.

The method according to the invention preferably comprises one or moreof the following steps: providing a donor substrate or a multilayerarrangement, producing modifications in the interior of the donorsubstrate or the multilayer arrangement by means of LASER beams,wherein, by means of the modifications, a detachment region ispredefined, along which the solid-body layer is separated from the donorsubstrate or the multilayer arrangement, removing material of the donorsubstrate or of the multilayer arrangement starting from a surfaceextending in the peripheral direction of the donor substrate towards thecentre of the donor substrate or the multilayer arrangement, inparticular so as to produce a peripheral indentation, wherein thedetachment region is exposed by the material removal, separating thesolid-body layer from the donor substrate or the multilayer arrangement,wherein the donor substrate or the multilayer arrangement is weakened inthe detachment region by the modifications in such a way that thesolid-body layer detaches from the donor substrate or the multilayerarrangement as a result of the material removal or, after the materialremoval, such a number of modifications are produced that the donorsubstrate or the multilayer arrangement is weakened in the detachmentregion in such a way that the solid-body layer detaches from the donorsubstrate or the multilayer arrangement or a stress-producing layer isproduced or arranged on a surface of the donor substrate or multilayerarrangement, which surface is oriented at an incline relative to theperipheral surface and in particular is planar, and mechanical stressesare produced in the donor substrate or in the multilayer arrangement bya thermal treatment of the stress-producing layer, wherein a crack forseparation of a solid-body layer is created by the mechanical stressesand propagates, starting from the surface of the donor substrate ormultilayer arrangement exposed by the material removal, along themodifications.

This solution is advantageous since an edge of the donor substrate orthe multilayer arrangement, in the region of which modifications forfurther forming of the detachment region can be produced only in a verycomplex manner, can be removed or reduced or modified. A radial materialremoval is thus hereby provided, as a result of which the distance ofthe peripheral surface from the detachment region is reduced.

Further preferred embodiments are the subject of the dependent claimsand/or the following parts of the description.

The detachment region predefined by the modifications, in accordancewith a further preferred embodiment of the present invention, is furtherdistanced from the peripheral surface of the donor substrate before thematerial removal than after the material removal. This embodiment isadvantageous since the detachment region thus can be easily produced andyet is still preferably adjacent to the outer peripheral surface of thedonor substrate after the material removal.

The modifications for predefining the detachment region, in accordancewith a further preferred embodiment of the present invention, areproduced before the material removal, and, by means of the materialremoval, a reduction of the distance of the detachment region to lessthan 10 mm, in particular to less than 5 mm and preferably to less than1 mm, is achieved at least at specific points, or the modifications forpredefining the detachment region are produced after the materialremoval, wherein the modifications are produced in such a way that thedetachment region is distanced, at least at specific points, by lessthan 10 mm, in particular less than 5 mm, and preferably less than 1 mm,from a surface exposed by the material removal. At least individualmodifications of the detachment region are particularly preferably partof the surface of the donor substrate that is exposed by the materialremoval and that is peripheral at least in part, preferably completely.

In accordance with a further preferred embodiment of the presentinvention, the material is removed by means of ablation beams, inparticular ablation LASER beams, or ablation fluids, or an indentationwith an asymmetrical design is produced by the material removal, or thematerial removal is performed at least in portions in the peripheraldirection of the donor substrate as a reduction of the radial extent ofthe donor substrate, in the entire region between the detachment regionand a surface of the donor substrate distanced homogeneously from thedetachment region.

The aforementioned object can be achieved additionally or alternativelyby a method for separating solid-body slices from a donor substrate,said method preferably comprising at least the following steps:providing a donor substrate, removing material of the donor substratestarting from a surface extending in the peripheral direction of thedonor substrate towards the centre of the donor substrate in order toproduce an indentation, wherein the material is removed by means ofablation LASER beams and/or the indentation is produced asymmetrically,producing modifications by means of further LASER beams in the interiorof the donor substrate, wherein the modifications are positioned in sucha way that they are adjacent to the indentation, wherein the solid-bodyslice is detached from the donor substrate by the produced modificationsor a stress-producing layer is produced or arranged on a surface whichis oriented at an incline relative to the peripheral surface and inparticular is planar, and mechanical stresses are produced in the donorsubstrate by a thermal treatment of the stress-producing layer, whereina crack for separation of a solid-body layer is produced by themechanical stresses and propagates, starting from the indentation, alongthe modifications.

The modifications are achieved here preferably using the shortestpossible pulses in the smallest possible vertical region by focusing inthe material with a high numerical aperture.

During the ablation, the ablation LASER beams are focused on the surfaceof the material with a lower numerical aperture and often a wavelengthabsorbed linearly by the material. The linear absorption of the ablationLASER beams at the material surface leads to an evaporation of thematerial (the ablation), i.e. to a material removal, and not only to astructural change.

This solution is advantageous since an edge region of the donorsubstrate is processed by means of a material-removing treatment, bymeans of which the outer edge of the donor substrate is displaced in theregion of the plane in which the crack propagates, towards the centre ofthe donor substrate. The displacement preferably occurs in the directionof the centre to such an extent that all LASER beams can penetrate thedonor substrate over the same planar surface, depending on thepenetration depth of the LASER beams and/or the angle of the LASER beamsto one another.

The indentation surrounds the donor substrate, in accordance with afurther preferred embodiment of the present invention, completely in theperipheral direction. This embodiment is advantageous since the crackcan be introduced into the donor substrate in a defined manner over theentire periphery of the donor substrate.

In accordance with a further preferred embodiment of the presentinvention, the indentation runs towards the centre as far as anindentation end that becomes increasingly narrower, in particular in awedge-like or notch-like manner, wherein the indentation end lies in theplane in which the crack propagates. This embodiment is advantageoussince a notch is created by the indentation end, which notch predefinesthe direction of propagation of the crack.

The asymmetric indentation, in accordance with a further preferredembodiment of the present invention, is produced by means of a grindingtool, which is negatively shaped at least in part in order to make theindentation. This embodiment is advantageous since the grinding tool canbe produced in accordance with the edge or indentation to be formed.

In accordance with a further preferred embodiment of the presentinvention, the grinding tool has at least two differently shapedprocessing portions, wherein a first processing portion is intended forprocessing of the donor substrate in the region of the underside of asolid-body slice to be separated and a second processing portion isintended for processing of the donor substrate in the region of theupper side of the solid-body slice to be separated from the donorsubstrate. This embodiment is advantageous since, in addition toshapings for improved crack formation, shapings for improved handlingcan also be produced by means of the grinding tool at the same time orat a different time on the donor substrate or on the portions of thedonor substrate forming one or more solid-body slices.

In accordance with a further preferred embodiment of the presentinvention, the first processing portion produces a deeper orlarger-volume indentation in the donor substrate than the secondprocessing portion, wherein the first processing portion and/or thesecond processing portion have/has curved or straight grinding faces.The first processing portion preferably has a curved main grinding faceand the second processing portion preferably likewise has a curvedsecondary grinding face, wherein the radius of the main grinding face isgreater than the radius of the secondary grinding face, the radius ofthe main grinding face is preferably at least twice as large as theradius of the secondary grinding face, or the first processing portionhas a straight main grinding face and the second processing portion hasa straight secondary grinding face, wherein, by means of the maingrinding face, more material is removed from the donor substrate thanwith the secondary grinding face, or the first processing portion has astraight main grinding face and the second processing portion has acurved secondary grinding face, or the first processing portion has acurved main grinding face and the second processing portion has astraight secondary grinding face.

The grinding tool preferably has a multiplicity of processing portions,in particular more than 2, 3, 4, 5, 6, 7, 8, 9 or 10 processingportions, in order to process a corresponding multiplicity of portionsof the donor substrate, which can be associated with differentsolid-body slices, in a machining or material-removing manner.

In accordance with a further preferred embodiment of the presentinvention, the ablation LASER beams are produced with a wavelength inthe range between 300 nm (UV ablation with frequency-tripled Nd:YAG orother solid-body laser) and 10 μm (CO₂ glass laser, often used forengraving and cutting processes), with a pulse length of less than 100microseconds and preferably less than 1 microsecond, and particularlypreferably less than 1/10 of a microsecond, and with a pulse energy ofmore than 1 μJ and preferably more than 10 μJ. This embodiment isadvantageous since the indentation can be produced by means of a LASERdevice and not by means of a grinding tool, which becomes worn.

The modifications in the donor substrate are produced in amaterial-dependent manner preferably with the following configurationsor LASER parameters: If the donor substrate consists of silicon or thedonor substrate comprises silicon, then nanosecond pulses or shorter(<500 ns), a pulse energy in the microjoule range (<100 μJ), and awavelength >100 nm are preferably used.

In the case of all other materials and material combinations, a pulse <5picoseconds, pulse energies in the microjoule range (<100 μJ), andwavelengths variable between 300 nm and 2500 nm are preferably used.

It is important here that a large aperture is provided in order to passdeep into the material. The aperture for producing the modifications inthe interior of the donor substrate is therefore preferably larger thanthe aperture for ablation of material by means of the ablation LASERbeams for producing the indentation. The aperture is preferably multipletimes larger, in particular at least 2, 3, 4, 5 or 6 times larger, thanthe aperture for ablation of material by means of the ablation LASERbeams for producing the indentation. The size of the focus for producinga modification, in particular with regard to the diameter of the focus,is preferably smaller than 10 μm, preferably smaller than 5 μm, andparticularly preferably smaller than 3 μm.

Alternatively, the present invention can relate to a method fordetaching solid-body slices from a donor substrate. Here, the methodaccording to the invention preferably comprises at least the followingsteps: providing a donor substrate, producing modifications in theinterior of the donor substrate by means of LASER beams, wherein theLASER beams penetrate the donor substrate over a planar surface of thedonor substrate, wherein the totality of LASER beams is inclinedrelative to the surface of the donor substrate in such a way that afirst portion of the LASER beams penetrates the donor substrate at afirst angle to the surface of the donor substrate and at least onefurther portion penetrates the donor substrate at a second angle to thesurface of the donor substrate, wherein the value of the first anglediffers from the value of the second angle, wherein the first portion ofthe LASER beams and the second portion of the LASER beams are focused inthe donor substrate in order to produce the modification, wherein thesolid-body slice is detached from the donor substrate by the producedmodifications or a stress-producing layer is produced or arranged on theplanar surface of the donor substrate and mechanical stresses areproduced in the donor substrate by a thermal treatment of thestress-producing layer, wherein a crack for separation of a solid-bodylayer is produced by the mechanical stresses and propagates along themodifications. The donor wafer and/or the LASER device emitting theLASER beams are/is preferably rotated about an axis of rotation duringthe production of the modifications. Additionally or alternatively tothe rotation of the donor wafer, the distance of the LASER beams fromthe centre of the donor wafer is particularly preferably changed.

The totality of LASER beams, in accordance with a further preferredembodiment of the present invention, is oriented in the same orientationrelative to the planar surface of the donor substrate for the productionof modifications in the region of the centre of the donor substrate andfor the production of modifications in the region of an edge of thedonor substrate provided in the radial direction.

This solution is advantageous since the total cross-section of the LASERbeam upon entry into the solid body contacts a planar surface, and sincehomogeneous damage then occurs in the depth. This homogeneous damage canbe produced as far as the outer edge of the donor substrate extending inparticular orthogonally to the planar surface. The modifications in theedge region of the donor substrate and in the region of the centre ofthe donor substrate can thus be produced by means of one processingstep.

In accordance with a further preferred embodiment of the presentinvention, the first portion of the LASER beams penetrates the donorsubstrate at a first angle to the surface of the donor substrate and thefurther portion of the LASER beams penetrates at a second angle forproduction of modifications in the region of the centre of the donorsubstrate and for production of modifications in the region of an edgeof the donor substrate provided in the radial direction, wherein thevalue of the first angle always differs from the value of the secondangle. The first angle and the second angle are preferably constant orunchanged or are not actively changed during the production of themodifications. This embodiment is advantageous since

In accordance with a further preferred embodiment of the presentinvention, the LASER device comprises a femtosecond LASER (fs LASER) ora picosecond LASER (ps LASER), and the energy of the LASER beams of theLASER (fs LASER or ps LASER) is preferably selected in such a way thatthe propagation of damage of each modification in the top layer and/orthe sacrificial layer is less than 3 times the Rayleigh length,preferably less than the Rayleigh length, and particularly preferablyless than a third of the Rayleigh length and/or the wavelength of theLASER beams of the fs LASER is selected in such a way that theabsorption of the top layer and/or of the sacrificial layer is less than10 cm⁻¹ and preferably less than 1 cm⁻¹ and particularly preferably lessthan 0.1 cm⁻¹ and/or the individual modifications are produced in eachcase as a result of a multi-photon excitation brought about by the fsLASER.

In accordance with a further preferred embodiment of the presentinvention the LASER beams for producing the modifications penetrate thedonor wafer over a surface that is part of the solid-body slice to beseparated. This embodiment is advantageous since the donor substrate isheated to a lesser extent, whereby the donor substrate is exposed onlyto low thermal stresses.

In accordance with a further preferred embodiment of the presentinvention, the ablation radiation comprises accelerated ions and/orplasma and/or LASER beams and/or is formed by electron beam heating orultrasound waves and/or is part of a lithographic method (electron beam,UV, ions, plasma) with at least one etching step following a previouslyexecuted photoresist coating and/or the ablation fluid is a liquid jet,in particular a water jet of a water jet cutting process.

The stress-producing layer, in accordance with a further preferredembodiment of the present invention, comprises a polymer, in particularpolydimethylsiloxane (PDMS), or consists thereof, wherein the thermaltreatment is preferably performed in such a way that the polymerexperiences a glass transition, wherein the stress-producing layer istemperature-controlled, in particular by means of liquid nitrogen, to atemperature below room temperature (i.e. to a temperature below 20° C.)or below 0° C. or below −50° C. or below −100° C. or below −110° C., inparticular to a temperature below the glass transition temperature ofthe stress-producing layer.

This embodiment is advantageous since it has been found that, due to thethermal treatment of the stress-producing layer, in particular byutilisation of the property changes of the material of thestress-producing layer occurring with the glass transition, the forcesnecessary to initiate and form a crack can be produced in a donorsubstrate.

The donor substrate preferably comprises a material or a materialcombination from one of the main groups 3, 4 and 5 of the Periodic Tableof Elements, such as Si, SiC, SiGe, Ge, GaAs, InP, GaN, Al2O3(sapphire), AIN, or consists of one or more of these materials. Thedonor substrate particularly preferably comprises a combination ofelements occurring in the third and fifth group of the Periodic Table ofElements. Conceivable materials or material combinations are for examplegallium arsenide, silicon, silicon carbide, etc. Furthermore, the donorsubstrate can comprise a ceramic (for example Al2O3—aluminium oxide) orcan consist of a ceramic, preferred ceramics being for exampleperovskite ceramics (such as Pb—, O—, Ti/Zr-containing ceramics) ingeneral, and lead magnesium niobates, barium titanate, lithium titanate,yttrium aluminium garnet, in particular yttrium aluminium garnetcrystals for solid-body laser applications, SAW (surface acoustic wave)ceramics, such as lithium niobate, gallium orthophosphate, quartz,calcium titanate, etc., in particular. The donor substrate thuspreferably comprises a semiconductor material or a ceramic material, orthe donor substrate particularly preferably consists of at least onesemiconductor material or a ceramic material. It is also conceivablethat the donor substrate comprises a transparent material or partiallyconsists of or is made of a transparent material, such as sapphire.Further materials which can be considered here as solid-body materialalone or in combination with another material are for example “wide bandgap” materials, InAlSb, high-temperature superconductors, in particularrare earth cuprates (for example YBa2Cu3O7).

The subject matter of patent application DE 2013 205 720.2 with thetitle: “Method for rounding edges of semiconductor parts produced from asemiconductor starting material, and semiconductor products produced bythis method” is hereby incorporated by reference in its full extent inthe subject matter of the present description.

The use of the word “substantially” in all cases in which this word isused within the scope of the present invention preferably defines adeviation in the range of 1% to 30%, in particular 1% to 20%, inparticular 1% to 10%, in particular 1% to 5%, in particular 1% to 2%,from the definition that would be given without the use of this word.

Further advantages, objectives and properties of the present inventionwill be explained on the basis of drawings accompanying the followingdescription, in which the solutions according to the invention areillustrated by way of example. Components or elements or method steps ofthe solutions according to the invention which in the figures coincideat least substantially in terms of their function can be denoted here bythe same reference signs, wherein these components or elements do nothave to be provided with reference signs or explained in all figures.

In the drawings:

FIG. 1 shows a multi-component wafer production process;

FIG. 2 shows an alternative sub-process of the multi-component waferproduction process according to the invention;

FIG. 3 shows a further or supplemented multi-component wafer productionprocess;

FIG. 4 shows a first example of an edge treatment within the scope ofthe invention;

FIG. 5 shows examples of contours of grinding tools as can be used inaccordance with the method shown in FIG. 4;

FIG. 6 shows a second example of an edge treatment within the scope ofthe invention; and

FIGS. 7a-7d show a third example of an edge treatment within the scopeof the invention; and

FIGS. 8a-8b show an illustration of a problem occurring when producingmodifications by means of LASER beams in the edge region of a donorsubstrate or multilayer arrangement;

FIG. 9 shows an example of an edge treatment within the scope of thesolid-body slice production or solid-body layer production according tothe invention;

FIG. 10 shows a further example of an edge treatment within the scope ofthe solid-body slice production or solid-body layer production accordingto the invention;

FIG. 11 shows an illustration that shows problems that occur with theproduction of modifications in a solid body if the modifications areproduced by means of LASER beams;

FIG. 12 shows an illustration that shows the different LASER beamangles;

FIGS. 13a /13 b show an illustration of a modification production stepand a schematic illustration of the produced modifications;

FIGS. 14a /14 b show two illustrations of modification production steps;and

FIG. 15 shows production of a modification with an aberrationadjustment.

FIG. 1 shows a number of steps of a method according to the inventionfor producing a multi-component wafer 1, in particular a MEMS wafer.

In accordance with this illustration, a bonding wafer 2 is firstprovided in a first step I., wherein at least one surface portion 4 ofthe bonding wafer 2 is formed by an oxide layer. A donor wafer 6 is alsoprovided in the first step I., wherein the donor wafer 6 is thicker thanthe bonding wafer.

In a second step II., the donor wafer 6 is brought into contact with thesurface portion 4 of the bonding wafer 2 formed by the oxide layer. Thisleads to the formation of a multilayer arrangement 8 by connection ofthe donor wafer 6 and of the bonding wafer 2 in the region of thecontact.

In a third step III., modifications 18 are produced in the interior ofthe donor wafer 6 for predefining a detachment region 11 for separationof the multilayer arrangement 8 into a separation part 14 and aconnection part 16, wherein the modifications 18 are produced before theformation of the multilayer arrangement 8 or after the formation of themultilayer arrangement 8.

Step IV. shows the step of separation of the multilayer arrangement 8along the detachment region 11 as a result of a weakening of themultilayer arrangement brought about by the production of a sufficientnumber of modifications, wherein the connection part 16 remains on thebonding wafer 2, and wherein the split-off separation part 14 has agreater thickness than the connection part 16.

The separation part 14 is then supplied in a further step to a treatmentdevice 24. The treatment device 24 produces an oxide layer by materialapplication and/or by material conversion, by means of which oxide layerat least one, preferably planar, surface of the separation part 14 isformed.

Before or after production of the oxide layer, a material-removing stepis preferably performed, in particular a polishing, lapping, etchingand/or chemical-mechanical polishing, by means of which at least onesurface or a surface portion of the detachment layer 14 or of thebonding wafer 2 is smoothed, i.e. experiences a roughness reduction atleast in part.

By means of the roughness reduction and the oxide layer production, inparticular an SiOx process, the separation part 14 is reconfigured intoa further bonding wafer 3. This further bonding wafer 3 is then used asbonding wafer 2 in accordance with the method described by steps I-IV.

FIG. 2 shows an alternative production of the modifications 18. Inaccordance with this variant the modifications 18 are produced beforethe production of a multilayer arrangement 8. This embodiment isadvantageous since the LASER beams 20 can penetrate the donor wafer 6over a surface of the donor wafer 6 which is part of the connection part16 once the donor wafer 6 has been divided.

FIG. 3 shows a further or further supplemented multi-component waferproduction process according to the invention, in particular a MEMSwafer production process. In accordance with this multi-component waferproduction process, a bonding wafer 2 and a donor wafer 6 are providedin a first step I. The bonding wafer 2 has an oxide layer on preferablyat least one surface, in particular on at least one planar surface 4.Here, the oxide layer can be produced by conversion of the startingmaterial of the bonding wafer 2 or by deposition or coating. The donorwafer 6 preferably does not have an oxide layer.

In step II., the bonding wafer 2 and the donor wafer 6 are connected toone another, in particular integrally bonded to one another. The oxidelayer or at least part of the oxide layer of the bonding wafer 2 ishereby directly superimposed or covered by the donor wafer 6. Thesurface of the oxide layer and the surface of the donor wafer 6, whichare connected to one another here, both particularly preferably have asurface finish provided by polishing, lapping, etching and/orchemical-mechanical polishing. The mean roughness Ra is preferably lessthan 76 μm, or less than 38 μm or less than 12.5 μm or less than 6 μm orless than 3 μm or less than 2.5 μm or less than 1.25 μm or less than 0.5μm.

In step III., the multilayer arrangement 8, in particular the donorsubstrate 6, is acted on by LASER beams 20 of a LASER device 22. TheLASER beams 20 cause modifications 18 of the material forming the donorwafer 6 to be created or produced in the interior of the donor wafer 6,in particular on account of a multi-photon excitation. A multiplicity ofmodifications 18 are preferably produced, wherein the individualmodifications 18 preferably lie in the same plane. The totality ofmodifications 18 thus constitutes a precise producible weakening of thedonor wafer at 6, which predefines the course of formation of a crackfor separating the donor wafer 6 into two parts in the sense of aperforation. The LASER beams 20, in accordance with the shown example,penetrate the donor wafer 6 over a surface of the donor wafer 6 which ispart of the thicker part following the splitting of the donor wafer 6into two parts.

An alternative production of modifications 18 is shown by FIG. 2.

In step IV., a stress-producing layer 10 is arranged or produced on apreferably further exposed and particularly preferably planar surface ofthe bonding wafer 2 and/or on a preferably further exposed andparticularly preferably planar surface of the donor wafer 6. Thestress-producing layer 10 is here preferably a polymer layer, inparticular a layer consisting of PDMS or comprising PDMS.

In step V., the stress-producing layer 10 arranged on the bonding wafer2 and/or the stress-producing layer 10 arranged on the donor wafer 6are/is exposed to a thermal treatment, whereby the stress-producinglayer 10 contracts and thus introduces mechanical stresses into themultilayer arrangement 8 in such a way that a crack forms and propagatesin the region of the modifications 18. The thermal treatment ispreferably provided via a cooling device 26, which particularlypreferably dispenses a free-flowing substance 28, which cools thestress-producing layer 10. The free-flowing substance 28 is herepreferably a fluid and particularly preferably liquid nitrogen. By meansof the crack, the donor wafer 6 is split into two parts: a connectionpart 16 and a separation part 14, wherein the connection part 16 remainson the bonding wafer 2 on account of the integrally bonded connection tothe bonding wafer 2, and the separation part 14 is separated. Theseparation part 14 and the connection part 16 both have a wafer-likedesign. The separation part 14 is preferably thicker than the connectionpart 16, the separation part 14 is preferably at least 1.25 times or atleast 1.5 times or at least 1.75 times or at least 2 times or at least2.25 times or at least 2.5 times or at least 2.75 times or at least 3times or at least 3.25 times or at least 3.5 times or at least 3.75times or at least 4 times or at least 4.25 times or at least 4.5 timesor at least 4.75 times or at least 5 times or at least 5.25 times or atleast 5.5 times or at least 5.75 times or at least 6 times or at least6.25 times as thick as the connection part 16. The thickness of theconnection part 16 is preferably determined by the mean distance of theplanar surfaces of the connection part 16 from one another. Thethickness of the separation part 14 is preferably determined by the meandistance of the planar surfaces of the separation part 14 from oneanother.

In step VI, the stress-producing layers 10 are removed from the producedmulti-component wafer 1, in particular MEMS wafer 1, by cleaning and arepreferably likewise removed from the separation part 14.

The separation part 14 is then fed in a further step to a treatmentdevice 24. The treatment device 24 produces an oxide layer by materialapplication and/or by material conversion, by means of which oxide layerat least one preferably planar surface of the separation part 14 isformed.

Before or after production of the oxide layer, a material-removing stepis preferably performed, in particular a polishing, lapping, etchingand/or chemical-mechanical polishing, by means of which at least onesurface or a surface portion of the detachment layer 14 and/or of thebonding wafer 2 is smoothed, i.e. experiences a roughness reduction atleast in part.

Due to the roughness reduction and the oxide layer production, theseparation part 14 is reconfigured to form a further bonding wafer 3.This further bonding wafer 3 is then used as bonding wafer 2 inaccordance with the method described by steps I-VI.

The present invention thus relates to a method for producing amulti-component wafer 1, in particular a MEMS wafer 1. The methodaccording to the invention preferably comprises at least the followingsteps: providing a bonding wafer 2, wherein at least one surface portion4 of the bonding wafer 2 is formed by an oxide layer, providing a donorwafer 6, wherein the donor wafer 6 is thicker than the bonding wafer 2,bringing the donor wafer 6 into contact with the surface portion 4 ofthe bonding wafer 2 formed by the oxide layer, forming a multilayerarrangement 8 by connecting the donor wafer 6 and the bonding wafer 2 inthe region of the contact, arranging or producing a stress-producinglayer 10 on at least one exposed planar surface 12 of the multilayerarrangement 8, thermally treating the stress-producing layer in order toproduce mechanical stresses within the multilayer arrangement 8, whereinthe stresses in the portion of the multilayer arrangement 8 formed bythe donor wafer 6 are so great that a crack forms in the donor wafer 6,by means of which crack the donor wafer 6 is split into a separationpart 14 and a connection part 16, wherein the connection part 16 remainson the bonding wafer 2, and wherein the split-off separation part 14 hasa greater thickness than the connection part 16.

The present invention thus relates to a method for producing amulti-component wafer, in particular a MEMS wafer. The method accordingto the invention comprises at least the following steps: providing abonding wafer 2, wherein at least one surface portion 4 of the bondingwafer 2 is formed by an oxide layer, providing a donor wafer 6, whereinthe donor wafer 6 is thicker than the bonding wafer 2, bringing thedonor wafer 6 into contact with the surface portion 4 of the bondingwafer 2 formed by the oxide layer, forming a multilayer arrangement 8 byconnecting the donor wafer 6 and the bonding wafer 2 in the region ofthe contact, producing modifications 18 in the interior of the donorwafer 6 for predefining a detachment region 11 for separating themultilayer arrangement 8 into a separation part 14 and a connection part16, wherein the modifications 18 are produced prior to the formation ofthe multilayer arrangement 8 or after the formation of the multilayerarrangement 8, separating the multilayer arrangement along thedetachment region as a result of a weakness of the multilayerarrangement brought about by the production of a sufficient number ofmodifications or as a result of a production of mechanical stresses inthe multilayer arrangement, wherein the connection part 16 remains onthe bonding wafer 2, and wherein the split-off separation part 14 has athickness greater than the connection part 16.

FIG. 4 shows 5 illustrations, by means of which examples of thesolid-body slice production or wafer production according to theinvention are shown. Illustration 1 shows a grinding tool 122, which hastwo processing portions 24 distanced from one another, which each form amain grinding face 132. The main grinding faces 132 are formed here sothat they produce indentations 16 in a donor substrate 12. The grindingtool 122 is preferably formed as a rotary grinding tool or as a beltgrinding tool.

Illustration 2 of FIG. 4 shows a donor substrate 12, in whichindentations 16 have been produced by means of the grinding tool 122.Here, the indentations 16 are distanced preferably uniformly from oneanother in the longitudinal direction of the donor wafer 12, wherein itis also conceivable for the distances to be of different sizes. Inaccordance with the second illustration in FIG. 5, modifications 110 arealso produced in the donor substrate 12 by means of a LASER device 146.The LASER device 146 for this purpose emits LASER beams 112, whichpenetrate the donor substrate 12 over a preferably planar surface 116 ofthe donor substrate 12, and a modification 110 of the lattice structureof the solid body or of the donor substrate 12 is produced or broughtabout at a focus point 148, in particular by a multi-photon excitation.Here, the modification 110 is preferably a material conversion, inparticular a conversion of the material into another phase, or amaterial degradation.

The third illustration shows that a stress-producing layer 114 has beenproduced or arranged on the surface 116 over which the LASER beams 112were introduced into the donor substrate 12 for production of themodifications 110. The stress-producing layer 114 is thermally treatedor temperature-controlled, in particular cooled, in order to producemechanical stresses in the donor substrate 12. By means of the thermaltreatment of the stress-producing layer 114, the stress-producing layer114 contracts, whereby the mechanical stresses are produced in the donorsubstrate 12. The previously produced indentations 16 form notches,through which the mechanical stresses can be conducted in such a waythat the crack 120 resulting from the stresses propagates in a targetedmanner in the region of crack formation predefined by the modifications110. The indentation ends 118 therefore are preferably adjacent to theparticular region of crack formation predefined by the modifications110. It is preferably always the case that only precisely the solid-bodylayer 11 of which the indentation 16 is distanced least far from thestress-producing layer 114 is split off.

Illustration 4 shows a state following crack propagation. The solid-bodyslice 11 has been split off from the donor substrate 12, and thestress-producing layer 114 initially still remains on the surface 116 ofthe solid-body slice 11.

Reference sign 128 denotes the side of the solid-body slice 11 which isdenoted here as the underside of the solid-body slice 11, and referencesign 130 denotes the side of the solid-body slice 11 which is denotedhere as the upper side of the solid-body slice 11.

Illustration 5 shows a method in which the solid-body layer 11 isdetached from the donor substrate 12 without a stress-producing layer114. Here, following production of the indentation 16, so manymodifications 110 are preferably produced by means of LASER beams 112,that the solid-body layer 11 detaches from the donor substrate 12. Thedashed line Z here preferably characterises a centre or an axis ofrotation of the donor substrate 12. The donor substrate 12 is preferablyrotatable about the axis of rotation Z.

FIG. 5 shows two illustrations, wherein each illustration shows agrinding tool 122 with a specific contour. If reference is made to aplanar, straight or curved portion with regard to the grinding tool,this is always understood to mean a portion of the shown contour. Ofcourse, the grinding tool 122 can be formed for example as a rotarygrinding tool, whereby the portions adjacent to the contour in theperipheral direction would preferably extend in a curved manner in theperipheral direction. The grinding tool 122 shown in the firstillustration of FIG. 5 has a first processing portion 124, which has acurved main grinding face 132, and has a second processing portion 126,which has a curved secondary grinding face 134, wherein the radius ofthe main grinding face 132 is greater than the radius of the secondarygrinding face 134, preferably the radius of the main grinding face 132is at least twice, three times, four times or five times as great as theradius of the secondary grinding face 134.

In accordance with the second illustration of FIG. 5, the firstprocessing portion 124 of the grinding tool 122 has a straight maingrinding face 132 and the second processing portion 126 has a straightsecondary grinding face 134, wherein more material is removed from thedonor substrate 12 by means of the main grinding face 132 than by meansof the secondary grinding face 134.

The grinding tools 122 shown in FIG. 5 and the indentations produced bythe shown grinding tools 122 can likewise be used in respect of theillustrations shown in FIG. 4.

FIG. 6 shows a further variant of the method according to the invention.By means of a comparison of the first and fifth illustration, it can beseen that the modifications 110 produced by means of the LASER beams112, in the case of a planar surface 116, can be produced closer to theedge 144 than if the tip of the edge 117 of the surface 116 is removed,as shown in the fifth illustration. The LASER beams 112 here penetratethe donor substrate 12, similarly to the modification productionexplained with reference to FIG. 4.

The second illustration of FIG. 6 shows the production of an indentation16 starting from a peripheral surface 14 in the direction of the centreZ of the donor substrate 12, wherein the indentation is produced bymeans of ablation LASER beams 18 of an ablation LASER (not shown). Theablation LASER beams here preferably evaporate the material of the donorsubstrate 12 in order to produce the indentation 16.

Illustration 3 of FIG. 6 corresponds substantially to illustration 3 ofFIG. 5, wherein merely the form of the indentation here is notasymmetrical, but instead is symmetrical. In accordance with thisillustration as well, a stress-producing layer 114 is thus produced orarranged on the donor substrate 12 and is thermally treated, inparticular by means of liquid nitrogen, in order to produce mechanicalstresses for initiating a crack 120.

Illustration 4 of FIG. 6 shows the solid-body slice 11 split off fromthe donor substrate 12, with the stress-producing layer still arrangedon said solid-body slice.

It can also be seen from illustration 5 of FIG. 6 that in the case of adonor substrate 12 of which the tip of the edge 117 is processed, theindentation 16 to be produced by means of ablation LASER beams 18 mustreach further in the direction of the centre of the donor substrate 12than if the tip of the edge 117 is not processed. Here, however, it isalso conceivable that the indentation is not produced by means ofablation LASER beams 18, but instead by means of a grinding tool 122 (asis known for example from FIGS. 4 and 5).

FIG. 7a shows an additional or alternative solution according to theinvention for the separation of solid-body layers 11 from a donorsubstrate 12. In accordance with FIG. 7a , a detachment region 111 isproduced in the interior of the donor substrate 2. The modifications 110are preferably distanced here from a peripheral delimiting face 150 ofthe donor substrate 12. The modifications 110 are preferably producedsimilarly to illustration 2 of FIG. 4. Here, it is conceivable that theLASER beams 112 are introduced into the donor substrate 12 from below orfrom above, i.e. over the surface 116.

FIG. 7b schematically shows the processing of the donor substrate 12 bymeans of an ablation tool 122, in particular a tool for machining thedonor substrate 12, such as a grinding tool 122. By means of theprocessing, material is removed, at least in portions in the peripheraldirection of the donor substrate 12, in the entire region between thedetachment region and a surface of the donor substrate 12 distancedpreferably homogeneously, in particular in parallel, from the detachmentregion, for reduction of the radial extent of the donor substrate 12.The material is preferably removed in an annular manner, in particularwith a constant or substantially constant radial extent.

FIG. 7c shows an example of a state after the removal of the material.Here, it is conceivable for example that the material is removed in theaxial direction of the donor substrate 12 up to the detachment plane, ortherebeneath or thereabove.

FIG. 7d shows a state following the separation or detachment of thesolid-body layer 11 from the donor substrate 12.

FIGS. 8a and 8b show a problem in the edge region of the donor substrate12 occurring with the production of modifications by means of LASERbeams 112. By means of the different refractive indices in the air andin the donor substrate, the LASER beam portions 138, 140 of a LASER beam112 do not coincide exactly with one another, thus resulting inundesirable effects, such as the production of defects at undesirablelocations, an undesirable local heating, or a prevention of theproduction of a modification.

FIG. 8b shows that a problem-free production of modifications 110 can beprovided only if the modification 110 to be produced is distanced fromthe peripheral surface of the donor substrate 12 to such an extent thatboth LASER beam portions 138, 140 are each refracted through materialwith the same refractive index and preferably over the same distance.However, this means that the production of the modification, as itoccurs in the region distanced from the edge region, cannot be readilyextended to the edge region.

The present invention thus relates to a method for separating solid-bodyslices 11 from a donor substrate 12. Here, the method according to theinvention comprises the following steps:

Providing a donor substrate 12, removing material of the donor substrate12 starting from a surface 14 extending in the peripheral direction ofthe donor substrate 2 towards the centre Z of the donor substrate 12 inorder to produce an indentation 16, wherein the material is removed bymeans of ablation LASER beams 18 and/or the indentation 16 is producedasymmetrically, producing modifications 110 in the interior of the donorsubstrate 12 by means of further LASER beams 112, wherein themodifications 10 are positioned in such a way that they are adjacent tothe indentation 16, wherein the solid-body slice 11 is detached from thedonor substrate 12 by means of the produced modifications 110, or astress-producing layer 114 is produced or arranged on a surface 116 ofthe donor substrate 12, which surface is oriented at an incline to theperipheral surface and in particular is planar, and mechanical stressesare produced in the donor substrate 12 by means of a thermal treatmentof the stress-producing layer 114, wherein a crack 120 for separating asolid-body layer 11 is created by the mechanical stresses andpropagates, starting from the indentation 16, along the modifications110.

The present invention thus relates to a method for separating solid-bodyslices 11 from a donor substrate 12. Here, the method according to theinvention comprises the following steps:

producing modifications 110 in the interior of the donor substrate 12 bymeans of LASER beams 112, wherein a detachment region is predefined bythe modifications 110, along which detachment region the solid-bodylayer 11 is separated from the donor substrate 12 or the multilayerarrangement,

removing material of the donor substrate 12, starting from a surface 14extending in the peripheral direction of the donor substrate 12 towardsthe centre Z of the donor substrate 12, in particular in order toproduce a peripheral indentation 16, wherein the detachment region isexposed by the material removal, separating the solid-body layer fromthe donor substrate, wherein the donor substrate is weakened in thedetachment region by the modifications in such a way that the solid-bodylayer 11 is detached from the donor substrate 12 as a result of thematerial removal or such a number of modifications are produced afterthe material removal that the donor substrate is weakened in thedetachment region in such a way that the solid-body layer 11 is detachedfrom the donor substrate 12 or a stress-producing layer 114 is producedor arranged on a surface 16 of the donor substrate 12, which surface isoriented at an incline to the peripheral surface and in particular isplanar, and mechanical stresses are produced in the donor substrate 12by means of a thermal treatment of the stress-producing layer 114,wherein by means of the mechanical stresses a crack 120 for separating asolid-body layer 11 is created and propagates, starting from the surfaceof the donor substrate exposed by the material removal, along themodifications 110.

FIG. 9 shows 4 illustrations. In the first illustration of FIG. 9, adonor substrate 22 is shown, which is acted on by LASER beams 212. TheLASER beams 212 are inclined in their totality relative to the surface216 over which the LASER beams penetrate the donor substrate 22, in sucha way that the inclination deviates from an angle of 90°. A firstportion 236 of LASER beams 212 is preferably oriented at a first angle238 relative to the surface 216, and a further portion 240 of LASERbeams 212 is oriented at a second angle 242 relative to the surface 216.The LASER beam portions 236 and 240, for production of all modifications212 produced for separation of a specific solid-body layer 21, arepreferably always inclined identically relative to the surface 216 overwhich the LASER beam portions 236, 240 penetrate the donor substrate 22.It can also be inferred from the first illustration of FIG. 12 that thefocus point 248 can be guided in the donor substrate 22 as far as theedge 244 or directly adjacently to the edge 244 for production ofmodifications 210 on account of the inclined LASER beam portions 236,240.

It can also be deduced from illustration 2 of FIG. 9 that, in accordancewith the LASER beam portions 236, 240 oriented at an incline, amaterial-removing treatment of the edge 244 of the donor substrate 22 isnot necessary or is only necessary to a significantly reduced extent.The stress-producing layer 214 arranged or produced on the surface 216causes a production of mechanical stresses in the donor substrate 22,whereby a crack 220 propagates in a very precisely guided manner fromthe edge 244 into the donor substrate 22 on account of the modifications210 produced as far as the edge 244.

Illustration 3 of FIG. 9 shows a solid-body slice 21 completely splitoff from the donor substrate 22, wherein the solid-body slice 21preferably has not experienced any edge tip treatment in accordance withthis embodiment.

Illustration 4 of FIG. 9 indicates that a solid-body slice 21 can beremoved from the donor substrate 22 likewise by production ofmodifications 210 by means of LASER beams 236, 240 (without astress-producing layer 214).

The present invention thus relates to a method for separating solid-bodyslices 21 from a donor substrate 22. Here, the method according to theinvention comprises the following steps:

providing a donor substrate 22, producing modifications 210 in theinterior of the donor substrate 22 by means of LASER beams 212, whereinthe LASER beams 212 penetrate the donor substrate 22 over a planarsurface 216 of the donor substrate 22, wherein the totality of the LASERbeams 212 is inclined relative to the planar surface 216 of the donorsubstrate 22 in such a way that a first portion 236 of the LASER beams212 penetrates the donor substrate 22 at a first angle 238 to the planarsurface 216 of the donor substrate 22 and at least one further portion240 of the LASER beams 212 penetrates the donor substrate 22 at a secondangle 242 to the planar surface 216 of the donor substrate 22, whereinthe value of the first angle 238 differs from the value of the secondangle 242, wherein the first portion 236 of the LASER beams 212 and thefurther portion 240 of the LASER beams 212 are focused in the donorsubstrate 22 in order to produce the modification 210, wherein thesolid-body slice 21 is detached from the donor substrate 22 by theproduced modifications 210 or a stress-producing layer 214 is producedor arranged on the planar surface 216 of the donor substrate andmechanical stresses are produced in the donor substrate 22 by means of athermal treatment of the stress-producing layer 214, wherein a crack 220for separating a solid-body layer 21 is created by the mechanicalstresses and propagates along the modifications 210.

FIG. 10 shows a further variant of the method according to theinvention. By means of a comparison of the first and the fifthillustration, it can be seen that the modifications 210 produced bymeans of the LASER beams 212, in the case of a planar surface 216, canbe produced closer to the edge 244 than if the tip of the edge 217 isremoved from the surface 216, as is shown in the fifth illustration. TheLASER beams 212 here penetrate the donor substrate 22 similarly to theproduction of a modification explained with reference to FIG. 9.

The second illustration of FIG. 10 shows the production of anindentation 26 starting from a peripheral surface 24 towards the centreZ of the donor substrate 22, wherein the indentation is produced bymeans of ablation LASER beams 28 of an ablation LASER (not shown). Theablation LASER beams here preferably evaporate the material of the donorsubstrate 22 in order to produce the indentation 26.

Illustration 3 of FIG. 10 corresponds substantially to illustration 3 ofFIG. 9, wherein merely the form of the indentation here is notasymmetrical, but instead is symmetrical. In accordance with thisillustration, a stress-producing layer 214 is thus likewise produced orarranged on the donor substrate 22 and is thermally treated, inparticular by means of liquid nitrogen, in order to produce mechanicalstresses for initiating a crack 220.

Illustration 4 of FIG. 10 shows the solid-body slice 21 split off fromthe donor substrate 2, with the stress-producing layer still arranged onsaid solid-body slice.

It can also be seen from illustration 5 of FIG. 10 that in the case of adonor substrate 22 of which the tip of the edge 217 is processed, theindentation 26 to be produced by means of ablation LASER beams 28 mustreach further in the direction of the centre of the donor substrate 22than if the tip of the edge 217 is not processed. Here, however, it isalso conceivable that the indentation is not produced by means ofablation LASER beams 28, but instead by means of a grinding tool 222 (asis known for example from FIG. 9).

FIG. 11 shows an arrangement in accordance with which a LASER beam 212is oriented parallel to the longitudinal axis L. This illustrationadditionally or alternatively also shows a LASER beam 260 inclined at anangle al relative to the longitudinal axis L. Both LASER beams 212 and260 can serve here for the production of the modifications 210, by meansof which a detachment region 211 is predefined. It is conceivable herethat a plurality of the modifications 210 are produced by the LASER beam212, which is not inclined relative to the longitudinal axis L, and thatthe modifications 210 in the edge region, that is to say at a distanceof less than 10 mm, in particular of less than 5 mm or of less than 2 mmor of less than 1 mm or of less than 0.5 mm from the peripherallyextending surface (peripheral surface), are produced by the LASER beam260 inclined relative to the longitudinal axis L.

Alternatively, it is also conceivable that all modifications 210 of thedetachment region or the plurality of modifications 210 of thedetachment region 211 are produced by the LASER beam 260 inclined at anangle α1 relative to the longitudinal axis L.

Additionally or alternatively, within the sense of the presentinvention, the modifications 210 in the edge region can be produced by afurther LASER beam 262, 264 inclined relative to the longitudinal axis Lof the donor substrate 22, wherein this LASER beam preferably penetratesthe donor substrate 22 over a peripheral surface of the donor substrate22. It can be seen from the illustration that a LASER beam 262, forproduction of the modifications 210 in the edge region, can beintroduced into the donor substrate 22 over the peripheral surface forexample at an angle α2, which is greater than 0° and smaller than 90°,relative to the detachment region 211. It can also be seen from theillustration that a LASER beam 264, in order to produce themodifications 210, can be introduced into the donor substrate 22 overthe peripheral surface of the donor substrate 22 in the direction ofextent of the detachment region 211. Here, the LASER beam 264 ispreferably inclined at an angle α3, between 80° and 100°, in particular90° or substantially 90°, relative to the longitudinal axis L of thedonor substrate 22.

A modification 210 can thus be produced in the region of the edge by oneof the LASER beams 260, 262, 264.

Furthermore, in accordance with the invention, the statements providedwith reference to FIG. 9 can be applied or transferred similarly to thesubjects shown in FIG. 211, and vice versa.

FIG. 13a shows a detachment region 211 produced just short from the edgeregion. FIG. 13a also shows the production of modifications by means ofa LASER beam 264. A plurality of modifications 210 are preferablyproduced in the radial direction by the LASER beam 264, in particularover a line, with increasingly greater distances from the centre or anaxis of rotation (which extends preferably orthogonally to the planarsurface 216 of the donor substrate 22) of the donor wafer 22.

FIG. 13b schematically shows a state following the production of themodifications 210. In accordance with this illustration the detachmentregion 211 is formed as a modification layer extending completely in theinterior of the donor wafer 22.

FIGS. 14a and 14b show two variants for producing modifications 210 bymeans of LASER beams introduced over the peripheral surface.

In accordance with FIG. 14a , a multiplicity of modifications 210 areproduced over the same penetration point, through which the LASER beams264 penetrate the donor substrate 22. The LASER beams are focused intothe donor substrate 22 at different depths in the radial direction inorder to produce the modifications 210. The modifications 210 arepreferably produced with decreasing penetration depth of the LASER beamsor with increasingly shorter distance of the focus point from thepenetration point.

FIG. 14b shows the filament-like production of modifications. Themodifications 210 produced in the form of filaments are longer then amultiple of their cross-sectional extent, in particular for example 10times, 20 times, or 50 times longer.

FIG. 15 shows a LASER device 246, an aberration means 247, and asectional illustration of a donor substrate 2. The detailed illustrationof FIG. 15 shows the LASER beam 212 penetrating the donor wafer 22 overthe curved peripheral surface of the donor wafer 22, wherein the courseof the radiation adapted by means of the aberration means 247 isillustrated by the dashed lines.

The present invention therefore relates to a method for separatingsolid-body slices 21 from a donor substrate 22. The method according tothe invention comprises the following steps: providing a donor substrate22, producing at least one modification 10 in the interior of the donorsubstrate 2 by means of at least one LASER beam 212, wherein the LASERbeam 212 penetrates the donor substrate 22 over a planar surface 216 ofthe donor substrate 22, wherein the LASER beam 212 is inclined relativeto the planar surface 216 of the donor substrate 22, in such a way thatit penetrates the donor substrate at an angle that is unequal to 0° or180° relative to the longitudinal axis of the donor substrate, whereinthe LASER beam 212 is focused in the donor substrate 22 in order toproduce the modification 210, wherein the solid-body slice 21 isdetached from the donor substrate 22 by the produced modifications 210or a stress-producing layer 214 is produced or arranged on the planarsurface 216 of the donor substrate 22 and mechanical stresses areproduced in the donor substrate 22 by a thermal treatment of thestress-producing layer 214, wherein a crack 220 for separating asolid-body layer 21 is produced by the mechanical stresses andpropagates along the modifications 210.

1. A method for producing a multi-component wafer (1), in particular aMEMS wafer, at least comprising the following steps: providing a bondingwafer (2), wherein at least one surface portion (4) of the bonding wafer(2) is formed by an oxide layer, providing a donor wafer (6), whereinthe donor wafer (6) is thicker than the bonding wafer (2), bringing thedonor wafer (6) into contact with the surface portion (4) of the bondingwafer (2) formed by the oxide layer, forming a multilayer arrangement(8) by connecting the donor wafer (6) and the bonding wafer (2) in theregion of the contact, producing modifications (18) in the interior ofthe donor wafer (6) for predefining a detachment region (11) forseparating the multilayer arrangement (8) into a separation part (14)and a connection part (16) by means of at least one LASER beam, whereinthe modifications (18) are produced prior to the formation of themultilayer arrangement (8) or after the formation of the multilayerarrangement (8), separating the multilayer arrangement along thedetachment region as a result of a weakening of the multilayerarrangement brought about by the production of a sufficient number ofmodifications or as a result of production of mechanical stresses in themultilayer arrangement, wherein the connection part (16) remains on thebonding wafer (2), and wherein the split-off separation part (14) has agreater thickness than the connection part (16).
 2. The method accordingto claim 1, further comprising the following steps: cleaning theseparation part (14) and/or converting the separation part (14) into afurther bonding wafer (3) by a treatment of at least one surface portionof the separation part (14), and providing the further bonding wafer (3)so as to be brought into contact with a further donor wafer.
 3. Themethod according to claim 2, characterised in that the treatmentcomprises an oxidation process, in particular an SiOx process, wherebyan oxidation of the at least one surface portion is effected.
 4. Themethod according to any one of the preceding claims, characterised inthat the donor wafer (6) has a first thickness D1, the bonding wafer (2)has a second thickness D2, the separation part (14) has a thirdthickness D3, and the connection part (16) has a fourth thickness D4,wherein the thickness D1 is greater than the sum of the thicknesses D3and D4, wherein the sum of the thicknesses D3 and D4 is greater than thethickness D3, wherein the thickness D3 is greater than the thickness D2by a thickness DL.
 5. The method according to claim 4, characterised inthat the thickness DL is less than 200 μm, in particular less than 100μm, and is removed as a result of polishing and/or etching steps.
 6. Themethod according to any one of the preceding claims, characterised inthat the LASER beams (20) are emitted from a LASER device (22), whereinthe LASER device (22) is preferably a picosecond LASER or a femtosecondLASER or wherein the modifications (18) are local cracks in the crystallattice and/or material portions in the interior of the donor wafer (6)converted into another phase.
 7. The method according to claim 6,characterised in that the energy of the LASER beams (20) of the fs LASERis selected in such a way that the propagation of damage of eachmodification (18) in the donor substrate is less than 3 times theRayleigh length, preferably less than the Rayleigh length, andparticularly preferably less than a third of the Rayleigh length and/orthe wavelength of the LASER beams (20) of the fs LASER is selected insuch a way that the absorption of the donor substrate (6) is less than10 cm⁻¹ and preferably less than 1 cm⁻¹ and particularly preferably lessthan 0.1 cm^(−1 and/or) the individual modifications (18) in each caseare produced as a result of a multi-photon excitation brought about bythe fs LASER.
 8. The method according to claim 6 or 7, characterised inthat the LASER beams (20) for producing the modifications (18)infiltrate the donor wafer (6) over a surface which is part of theconnection part (16).
 9. The method according to any one of thepreceding claims, further comprising the following step: removingmaterial of the multilayer arrangement starting from a surface (14)extending in the peripheral direction of the multilayer arrangementtowards the centre (Z) of the multilayer arrangement, in particular soas to produce a peripheral indentation (16), wherein the detachmentregion is exposed by the material removal, separating the solid-bodylayer from the multilayer arrangement, wherein the multilayerarrangement is weakened in the detachment region by the modifications insuch a way that the solid-body layer (11) detaches from the multilayerarrangement as a result of the material removal or after the materialremoval, such a number of modifications are produced that the donorsubstrate is weakened in the detachment region in such a way that thesolid-body layer (11) detaches from the donor substrate (12) or astress-producing layer (114) is produced or arranged on a surface (116)of the donor substrate (12), which surface is oriented at an inclinerelative to the peripheral surface and in particular is planar, andmechanical stresses are produced in the donor substrate (12) by athermal treatment of the stress-producing layer (114), wherein a crack(120) for detachment of a solid-body layer (11) is produced as a resultof the mechanical stresses and propagates, starting from the surface ofthe donor substrate exposed by the material removal, along themodifications (110).
 10. The method according to claim 9, characterisedin that the detachment region predefined by the modifications (110) isdistanced further from the peripheral surface of the donor substrate(12) prior to the material removal than after the material removaland/or the modifications (110) for predefining the detachment region areproduced prior to the material removal, and by means of the materialremoval a reduction of the distance of the detachment region to lessthan 10 mm, in particular to less than 5 mm and preferably to less than1 mm, is achieved at least at specific points, or the modifications forpredefining the detachment region are produced after the materialremoval, wherein the modifications (110) are produced in such a way thatthe detachment region is distanced, at least at specific points, by lessthan 10 mm, in particular less than 5 mm, and preferably less than 1 mm,from a surface exposed by the material removal and/or the material isremoved by means of ablation beams (8), in particular ablation LASERbeams, or ablation fluids or an indentation (6) with an asymmetricaldesign is produced by the material removal or the material removal isperformed at least in portions in the peripheral direction of the donorsubstrate (12) as a reduction of the radial extent of the donorsubstrate (12), in the entire region between the detachment region and asurface of the donor substrate (12) distanced homogeneously from thedetachment region, and/or the indentation (16) surrounds the donorsubstrate (12) completely in the peripheral direction and/or theindentation (16) runs towards the centre (Z) as far as an indentationend (118) in a manner becoming increasingly narrower, in particular in awedge-like manner, wherein the indentation end (118) lies in the planein which the crack (120) propagates and/or the asymmetric indentation(16) is produced by means of a grinding tool (122) that is negativelyshaped at least in part in order to make the indentation (16) and/or thegrinding tool (122) has at least two differently shaped processingportions (124, 126), wherein a first processing portion (124) isintended for processing of the donor substrate (12) in the region of theunderside (128) of a solid-body slice (11) to be separated and a secondprocessing portion (126) is intended for processing the donor substrate(12) in the region of the upper side (130) of the solid-body slice (11)to be separated from the donor substrate (12) and/or the firstprocessing portion (124) produces a deeper or larger-volume indentation(16) in the donor substrate (12) than the second processing portion(126), wherein the first processing portion (124) and/or the secondprocessing portion (126) have/has curved or straight grinding faces(132, 134) and/or the first processing portion (124) has a curved maingrinding face (132) and the second processing portion (126) has a curvedsecondary grinding face (134), wherein the radius of the main grindingface (132) is greater than the radius of the secondary grinding face(134), the radius of the main grinding face (132) is preferably at leasttwice as large as the radius of the secondary grinding face (134) or thefirst processing portion (124) has a straight main grinding face (132)and the second processing portion (126) has a straight secondarygrinding face (134), wherein, by means of the main grinding face (132),more material is removed from the donor substrate (12) than with thesecondary grinding face (134) or the first processing portion (124) hasa straight main grinding face (132) and the second processing portion(126) has a curved secondary grinding face (134) or the first processingportion (124) has a curved main grinding face (132) and the secondprocessing portion (126) has a straight secondary grinding face (134)and/or the ablation LASER beams (18) are produced with a wavelength inthe range between 300 nm and 10 μm, with a pulse length of less than 100microseconds and preferably less than 1 microsecond, and particularlypreferably less than 1/10 of a microsecond, and with a pulse energy ofmore than 1 μJ and preferably more than 10 μJ and/or the material to beremoved in the entire region between the detachment region and thesurface distanced homogeneously from the detachment region describes anannular, in particular cylindrical design and/or wherein the LASER beams(112) are emitted from a LASER device (146), wherein the LASER device(146) is a picosecond LASER or a femtosecond LASER and/or the energy ofthe LASER beams (112), in particular of the fs LASER, is selected insuch a way that the propagation of damage of each modification (110) inthe donor substrate (12) is less than 3 times the Rayleigh length,preferably less than the Rayleigh length, and particularly preferablyless than a third of the Rayleigh length and/or the wavelength of theLASER beams (112), in particular of the fs LASER, is selected in such away that the absorption of the donor substrate (12) is less than 10 cm⁻¹and preferably less than 1 cm⁻¹ and particularly preferably less than0.1 cm⁻¹ and/or the individual modifications (110) are produced in eachcase as a result of a multi-photon excitation brought about by the LASERbeams (112), in particular the fs LASER, and/or the LASER beams (112)for producing the modifications (110) penetrate the donor wafer (12)over a surface (116) which is part of the solid-body slice (11) to beseparated and/or the stress-producing layer (114) comprises or consistsof a polymer, in particular polydimethylsiloxane (PDMS), wherein thethermal treatment is performed in such a way that the polymerexperiences a glass transition, wherein the stress-producing layer (114)is temperature-controlled, in particular by means of liquid nitrogen, toa temperature below room temperature or below 0° C. or below −50° C. orbelow −100° C. or below −110° C., in particular to a temperature belowthe glass transition temperature of the stress-producing layer (114)and/or the ablation radiation comprises accelerated ions and/or plasmaand/or LASER beams and/or is formed by electron beam heating orultrasound waves and/or is part of a lithographic method (electron beam,UV, ions, plasma) with at least one etching step following a previouslyexecuted photoresist coating and/or the ablation fluid is a liquid jet,in particular a water jet of a water jet cutting process.
 11. The methodaccording to any one of the preceding claims, characterised in that theLASER beam (212) or the LASER beams is/are inclined relative to theplanar surface (216) of the donor substrate (22) in such a way thatit/they penetrates/penetrate the donor substrate at an angle that isunequal to 0° C. or 180° C. relative to the longitudinal axis of thedonor substrate, wherein the LASER beam (212) is focused in the donorsubstrate (22) for production of the modification (210), whereinpreferably a first portion (236) of the LASER beam (212) penetrates thedonor substrate (22) at a first angle (238) to the planar surface (216)of the donor substrate (22) and at least one further portion (240) ofthe LASER beam (212) penetrates the donor substrate (22) at a secondangle (242) to the planar surface (216) of the donor substrate (22),wherein the value of the first angle (238) differs from the value of thesecond angle (242), wherein the first portion (236) of the LASER beam(212) and the further portion (240) of the LASER beam (212) are focusedin the donor substrate (22) for production of the modification (210).12. The method according to claim 11, characterised in that the totalityof the LASER beams (212) for producing modifications (210) in the regionof the centre (Z) of the donor substrate (22) and for producingmodifications (210) in the region of an edge (244) provided in theradial direction, in particular at a distance of less than 10 mm andpreferably of less than 5 mm and particularly preferably of less than 1mm from the edge of the donor substrate (22), is oriented in the sameorientation relative to the planar surface (216) of the donor substrate(22) and/or the first portion (236) of the LASER beams (212) penetratesthe donor substrate (22) at a first angle (238) to the planar surface(216) of the donor substrate (22) and the further portion (240) of theLASER beams (212) penetrates at a second angle (242) for production ofmodifications (210) in the region of the centre (Z) of the donorsubstrate (22) and for production of modifications (210) in the regionof an edge (244) of the donor substrate (22) provided in the radialdirection, wherein the value of the first angle (238) is alwaysdifferent from the value of the second angle (242) and/or wherein theLASER beams (212) are emitted from a LASER device (246), wherein theLASER device (246) is a picosecond LASER or a femtosecond LASER and/orthe energy of the LASER beams (212), in particular of the fs LASER, isselected in such a way that the propagation of damage of eachmodification (210) in the donor substrate (22) is less than 3 times theRayleigh length, preferably less than the Rayleigh length, andparticularly preferably less than a third of the Rayleigh length and/orthe wavelength of the LASER beams (212), in particular the fs LASER, isselected in such a way that the absorption of the donor substrate (22)is less than 10 cm⁻¹ and preferably less than 1 cm⁻¹ and particularlypreferably less than 0.1 cm⁻¹ and/or the individual modifications (210)are produced in each case as the result of a multi-photon excitationbrought about by the LASER beams (212), in particular of the fs LASERand/or the LASER beams (212) for producing the modifications (210)penetrate the donor wafer (22) over a surface (216) which is part of thesolid-body slice (21) to be detached and/or the LASER beam (212)penetrates the donor substrate (22) over a peripheral surface of thedonor substrate (22), in particular in the radial direction of the donorsubstrate (22), and/or the LASER beams (212) introduced into the donorsubstrate (22) over the peripheral surface produce modifications (210)which are elongate, in particular filament-like, and/or the LASER beams(212) introduced at a position of the peripheral surface of the donorsubstrate (22) are focussed at different penetration depths forproduction of a plurality of modifications (210), wherein themodifications (210) are produced here preferably starting from thedeepest depth to the shallowest depth and/or a means for aberrationadjustment is provided, and by the means an aberration adjustment of theLASER beams penetrating over the peripheral surface is made.
 13. Themethod according to any one of the preceding claims further comprisingthe following steps: arranging or producing a stress-producing layer(210) on at least one exposed surface (212) of the multilayerarrangement (28), thermally treating the stress-producing layer (210) inorder to produce the mechanical stresses within the multilayerarrangement (28), wherein the stresses in the portion of the multilayerarrangement (28) formed by the donor wafer (26) are so great that acrack is formed in the donor wafer (26) along the detachment region(211), by means of which crack the donor wafer (26) is split into theseparation part (214) and the connection part (216), wherein thestress-producing layer (210) comprises or consists of a polymer, inparticular polydimethylsiloxane (PDMS), wherein the thermal treatment isperformed in such a way that the polymer experiences a glass transition,wherein the stress-producing layer (210) is temperature-controlled, inparticular by means of liquid nitrogen, to a temperature below roomtemperature or below 0° C. or below −50° C. or below −100° C. or below−110° C., in particular to a temperature below the glass transitiontemperature of the stress-producing layer (210).
 14. Use of a substrateas donor wafer (6) and bonding wafer (2) in a multi-component waferproduction method, in particular a MEMS wafer production method, whereinthe substrate is arranged as donor wafer (6) on a further bonding wafer(3), which has an oxidation layer, wherein the donor wafer (6) isdivided, being split into a connection part (16) and a separation part(14), as a result of propagation of a crack, and wherein the separationpart (14) serves as bonding wafer (2) after treatment in a SiOx process,wherein the bonding wafer (2) is connected to a further donor substratein order to form a multilayer arrangement (8).
 15. A multi-componentwafer (1), in particular a MEMS wafer, at least comprising a bondingwafer (2), wherein at least one surface portion of the bonding wafer (2)is formed by an oxide layer, a connection part (16) split off from adonor wafer (6) as the result of propagation of a crack, wherein theconnection part (16) is arranged in an integrally bonded manner on asurface portion formed by the oxide layer, and wherein the bonding wafer(2) is a portion, prepared by means of an oxidation treatment, inparticular an SiOx treatment, of a separation part (14) separated from adonor wafer.